PROJECT SUMMARY The broad objective of the proposed studies is to apply design, dynamic testing, and material testing methods from Mechanical Engineering to better understand the impact of existing and new vocal fold implants and prostheses for vocal fold medialization, partial or total lamina propria reconstruction on the mechanical properties and dynamic response of native laryngeal tissue and, ultimately, voice quality. It is postulated that the systematic application of the proposed methods will eventually help the creation of implants and prostheses with mechanical behavior representative of native tissue that are robust and durable. Much work has been done on the use of vocal fold implants and prostheses for the surgical repair of vocal pathologies involving the lamina propria, such as scarring, sulcus vocalis, and atrophy, which remain challenging clinical problems in laryngology and phonosurgery. Biomaterials used have included specific types of fat, collagen, hyaluronic acid, fascia, and a variety of synthetic materials such as silicone, Gore-Tex, or hydroxyapatite. Previous work has been done without a detailed knowledge of the mechanical properties and response of the synthetic or biological materials used. This may have resulted in sub-optimal oscillatory function, and reduced voice quality. The present study aims at developing and evaluating synthetic models, implants, and prostheses with a set of mechanical properties that closely match measured data for human vocal fold tissue. Synthetic models of the larynx will be perfected and used for fundamental studies, as well as test beds for new implants. Digital image correlation methods will be developed in order to obtain dynamic, full field strain data and stress estimates that will help quantify the influence of prosthesis and implants on mechanical response. The dependence of the vocal folds resonance frequencies on tension, air flow rate, and implant design will be quantified. The influence of selected matrix proteins on the viscoelastic properties of the lamina propria will be measured in order to better under the consequences of the biological response of the tissue to foreign inclusions. The issues of bonding between implants and native tissue will be examined using atomic force microscopy.